Humans are veritable chemical factories—we manufacture thousands of substances and transport them, via our blood, throughout our bodies. Some of these substances can be used as indicators of our health status. A team of EPFL scientists has developed a tiny device that can analyze the concentration of these substances in the blood. Implanted just beneath the skin, it can detect up to five proteins and organic acids simultaneously, and then transmit the results directly to a doctor's computer. This method will allow a much more personalized level of care than traditional blood tests can provide. Health care providers will be better able to monitor patients, particularly those with chronic illness or those undergoing chemotherapy. The prototype, still in the experimental stages, has demonstrated that it can reliably detect several commonly traced substances.